Method of analyzing hollow anatomical structures for percutaneous implantation

ABSTRACT

A method of analyzing a hollow anatomical structure of interest for percutaneous implantation. The method comprises acquiring image data of an anatomical region of interest that includes the anatomical structure of interest, and generating a segmented model of the anatomical region of interest using the acquired image data. The method further comprises obtaining image(s) of the anatomical structure of interest by sectioning out intervening anatomical structures from the segmented model thereof, identifying one or more pertinent landmarks of the anatomical structure of interest in the acquired image(s), and measuring at least one of a circumference, a maximal diameter, or a minimal diameter of one or more features of the anatomical structure of interest contained in the acquired image(s) to determine an anatomical structure size. The method still further comprises reconciling the anatomical structure size and an implant size.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/034,251 filed Aug. 7, 2014, the entire contents of which are herebyincorporated by reference.

TECHNICAL FIELD

The present disclosure is generally related to periprocedural planningmethods, and more specifically, but not exclusively, to methods ofanalyzing hollow anatomical structures and planning for successfulpercutaneous implantation.

BACKGROUND

Non-invasive percutaneous implantation of stents, prosthetic valves, andother like implantable devices poses certain challenges for physicians.As opposed to surgically invasive procedures, such as open heartsurgery, for example, physicians performing non-invasive percutaneousimplantation procedures have a limited field of view and are generallylimited to the use of two-dimensional (2D) imaging modalities (e.g.,fluoroscopy, ultrasound, etc.) during the procedure. Accordingly,periprocedural planning for non-invasive procedures that involvesadvanced imaging strategies can lead to more successful percutaneousimplantation outcomes.

In the field of cardiology, transfemoral, transapical, and transaorticimplantation are promising alternatives to open heart surgery,particularly for inoperable and high surgical risk patients. However,because physicians are typically limited to 2D imaging during theprocedure itself, proper planning and evaluation is required toaccurately size the target vessel or chamber, choose an appropriatelysized implant, and determine both an ideal position for the implant anda point of access into the patient's body for performing theimplantation. Failure to accurately size the target vessel or chamber,choose the appropriately sized implant, and determine an ideal positionfor the implant and a point of access can result in, for example, valveregurgitation, laceration of the patient's native blood vessels, lungs,or other anatomical structures, and/or fatal pericardial tamponade.

SUMMARY

According to one embodiment, there is provided a method of analyzing ahollow anatomical structure of interest for percutaneous implantation.The method comprises acquiring image data relating to an anatomicalregion of interest that at least partially includes the anatomicalstructure of interest, and generating a segmented model of theanatomical region of interest using the acquired image data. The methodfurther comprises obtaining one or more images of the anatomicalstructure of interest by sectioning out intervening anatomicalstructures from the segmented model. The method still further comprisesidentifying one or more pertinent landmarks of the anatomical structureof interest in the one or more acquired images, and measuring at leastone of a circumference, a maximal diameter, or a minimal diameter of oneor more features of the anatomical structure of interest contained inthe one or more acquired images to determine an anatomical structuresize. The method yet still further comprises reconciling the anatomicalstructure size and an implant size.

According to another embodiment, there is provided a method of analyzinga hollow anatomical structure of interest for percutaneous implantation.The method comprises acquiring a model of an anatomical region ofinterest that at least partially includes the anatomical structure ofinterest, wherein the model is generated from image data relating to theanatomical structure of interest. The method further comprises obtainingone or more images of the anatomical structure of interest by sectioningout intervening anatomical structures from the model, and acquiring datarelating to the anatomical structure of interest from the one or moreimages of the anatomical structure of interest. The method still furthercomprises determining a size of an implant to be implanted into theanatomical structure of interest based on the acquired data.

According to yet another embodiment, there is provided a non-transitory,computer-readable storage medium storing instructions thereon that whenexecuted by one or more electronic processor(s) causes the processor(s)to carry out one or more steps of the method of: acquiring a model of ananatomical region of interest that at least partially includes theanatomical structure of interest, wherein the model is generated fromimage data relating to the anatomical structure of interest; obtainingone or more images of the anatomical structure of interest by sectioningout intervening anatomical structures from the model; acquiring datarelating to the anatomical structure of interest from the one or moreimages of the anatomical structure of interest; and determining a sizeof an implant to be implanted into the anatomical structure of interestbased on the acquired data.

BRIEF DESCRIPTION OF DRAWINGS

One or more embodiments of the invention will hereinafter be describedin conjunction with the appended drawings, wherein like designationsdenote like elements, and wherein:

FIG. 1 schematically and diagrammatically shows the structure of aportion of the human heart;

FIG. 2 is a schematically shows the operation of the mitral valve of ahuman heart;

FIGS. 3A-3J depict examples of prosthetic heart valves that can be usedduring percutaneous implantation procedures;

FIG. 4 is a flowchart of an illustrative embodiment of a method that maybe used to analyze hollow anatomical structures (e.g., valves, vessels,etc.) for percutaneous implantation procedures;

FIGS. 5-8 each comprise a three-dimensional (3D) model of the thoracicregion of a patient acquired from an imaging system, and various imagesof a mitral valve acquired by sectioning the 3D model in different ways;

FIGS. 9-29 are images/models of various thoracic structures acquiredfrom an imaging system;

FIG. 30 is a 3D rendering of a vessel structure derived from estimatedblood volume;

FIG. 31 is a 3D rendering of a mitral valve annulus with calcification;

FIGS. 32A and 32B are 3D renderings of a mitral valve annulus depictingthe sizes of possible replacement mitral valves;

FIGS. 33A-33C show different views of a 3D printed model of the rightatrium inferior vena cava junction having an implant disposed therein;

FIG. 34 is a schematic and block diagram of an illustrative embodimentof a system for performing the method illustrated in FIG. 4;

FIG. 35 is an image set comprising images of a mitral valve acquiredfrom an imaging system;

FIG. 36 is an enlarged view of the 3D image D of FIG. 35; and

FIG. 37 is the 3D image D of FIGS. 35 and 36 shown from a differentperspective.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT(S)

The method described herein can assist physicians in pre-operationalplanning and post-operative evaluation (also referred to as“periprocedural planning”) of various percutaneous procedures.Generally, the method includes the use of advanced imaging and modelingstrategies to accurately size the target hollow anatomical structure(e.g., valve, vessel, etc.), choose an appropriately sized implant,and/or determine an ideal position for the implant and/or a point ofaccess into the patient's body for performing the percutaneousimplantation. Although the method may be applicable to planning for andevaluating a variety of percutaneous procedures, it is particularlyapplicable to cardiac procedures, and even more particularly, cardiacprocedures involving the mitral valve. Accordingly, a predominantportion of the discussion below is directed to analysis of the mitralannulus for transcatheter mitral valve replacement (TMVR). However, itshould be understood that the various teachings could be applied to anynumber of percutaneous implantation procedures directed to differenthollow anatomical structures, for example, procedures directed to theaorta, the left atrial appendage, the inferior vena cava, or any othervessel or chamber.

A non-invasive, percutaneous approach to TMVR has been reported inGuerrero et al., “First in Human Percutaneous Implantation of a BalloonExpandable Transcatheter Heart Valve in a Severely Stenosed NativeMitral Valve,” Catheterization and Cardiovascular Interventions,83:E287-E291 (2014), the contents of which are incorporated herein byreference in their entirety. An improperly sized replacement valve orimproper placement of a valve during TMVR can lead to valve leakage andother deleterious effects. Moreover, procedures for mitral valveconditions such as severe mitral stenosis may posit certain challengesthat might not be applicable to the aortic valve and other valves thatare more simply or regularly shaped and distinguishable in operation.

FIGS. 1 and 2 depict a mitral valve 10. As the mitral valve opens, anasymmetric toroidal vortex forms during the early diastolic phase of thecardiac cycle as blood flows from the left atrium (not shown) to theleft ventricle 13. The unique saddle shape of the annulus 15 of themitral valve changes during the cardiac cycle, as it is largest in thediastolic phase when the valve is open and smallest in the systolicphase when the valve is closed. Unlike the aortic valve which is gatedby three leaflets, the mitral valve is gated by two leaflets: ananterior leaflet 17 and a posterior leaflet 19. Accurate sizing andplacement of replacement or prosthetic mitral valves requiresmeasurements of these native mitral valvular structures, particularly inlight of the relatively large number of various replacement valves thatare potentially available to physicians. A few examples of prostheticmitral valves are depicted in FIGS. 3A-3J; though it will be appreciatedthat the present disclosure is not intended to be limited solely tothose examples shown in FIGS. 3A-3J. Such a variety in prosthetic valveshapes is only beneficial if the mitral annulus is accurately sized anda precise location for placement of the prosthetic valve is determined.

Turning now to FIG. 4, there is shown an embodiment of a method 100 foranalyzing a hollow anatomic structure (e.g., a vessel, valve, etc.) ofinterest for non-invasive percutaneous implantation procedures. Aspreviously mentioned, the method will generally be described in thecontext of the mitral annulus and a percutaneous TMVR procedure.However, as also previously mentioned, it may be possible to apply thesame or similar methodology to a variety of hollow anatomical structuresand different percutaneous implantation procedures. According to oneembodiment, some or all of the method steps are automatically performedusing a system described more fully below and shown generally in FIG.34; alternatively, some or all of the steps may be performed by acombination of the system described below and a user (e.g., aphysician).

Beginning with step 102, image data relating to an anatomical region ofinterest that at least partially includes the anatomical structure ofinterest is acquired. In an illustrative embodiment, the image datacomprises computed tomography (CT) image data, and more particularly,two-dimensional (2D) CT data. It will be appreciated, however, that inother embodiments, the image data may comprise data acquired using animaging modality other than CT, for example, magnetic resonance imaging(MRI), echocardiogram imaging, or another suitable imaging modality.Accordingly, that the present disclosure is not intended to be limitedto any particular type of image data. For purposes of illustration andclarity, however, the description below will be primarily with respectto image data in the nature of CT image data.

In any event, for a transapical TMVR procedure or a transapicaltranscatheter aortic valve replacement (TAVR) procedure, for example,the anatomical region of interest is generally the thoracic cavity. Inone particular embodiment, step 102 includes taking a preliminarynon-contrast CT scan to calculate the number of segments or slicesneeded to cover the field of view. For a transapical procedure, the lungapices and the apex of the heart should be included in the field ofview. To acquire CT data of the anatomical region of interest, acontrast is administered to a patient. The contrast may be administered,for example, via an 18 or 20 gauge intravenous (IV) catheter placed inthe right forearm. For cardiac procedures, an electrocardiogram (EKG)may also be used to monitor the heart. The CT data should be acquiredduring an inspirational breath-hold because such an expansion of thethoracic cavity presents a scenario where it is more likely that thelungs will obstruct the devices (e.g., a guide wire, a catheter, etc.)used during the procedure. During the procedure, patients are typicallyintubated to hold inspiration. Accordingly, the lungs hold less airduring the procedure than during the pre-procedural scan which creates asafety margin of error between the inspirational breath-hold and amechanically ventilated end-expiration state.

In step 104, a 3D model is generated from the image data acquired instep 102. Accordingly, in an embodiment, the 2D CT image data acquiredin step 102 is utilized to generate or create a 3D CT model of theanatomical region of interest. The 3D model generated in step 104 maybe, for example, a segmented 3D model that can be used or manipulated tosection out intervening anatomical structures in order to obtain oracquire one or more images (e.g., 2D images) of the anatomical structureof interest. To perform this step, the data (e.g., CT data) acquired instep 102 is sent to a workstation that includes 3D reconstructionimaging/modeling software such as a Vitrea® workstation available fromVital Images, Inc. having a place of business in Minnetonka, Minn. Theimage data may be sent in DICOM format through a local network to theworkstation. The workstation may include graphics cards and may allowfor real-time or substantially real-time reconstruction of a segmented3D model (e.g. segmented 3D CT model) with corresponding 2D images ofthe anatomical region of interest. As discussed above, in an embodiment,the anatomical region of interest includes the anatomical structure ofinterest, which in a preferred embodiment, is the mitral valve. In thisembodiment, the workstation allows for substantially real-timereconstruction of the mitral valve in different phases of the cardiaccycle, which affects the shape and size of the mitral annulus.Intervening anatomical structures that may be sectioned out by removinglayers of the 3D model include, but are not limited to, skin, bone,lungs, heart, and pertinent coronary artery anatomy, and will varydepending upon the particular application. Pertinent coronary arteryanatomy may include the left anterior descending artery, coronary bypassgrafts if the patient has any, and any additional vessels of interest.In any event, the result of the sectioning out of intervening anatomicalstructures results in one or more images (e.g., 2D images) of theanatomical structure of interest.

Following step 104, method 100 may proceed to a step 106 of identifyingpertinent landmarks of the anatomical structure of interest containedwithin the image(s) of the anatomical structure of interest acquired bysectioning the model generated in step 104. This may be accomplished,for example, by playing the images in a cine loop, though othermeans/techniques for identifying the landmark(s) of interest mayadditionally or alternatively be used. Pertinent landmarks applicable toany cardiac procedure may include, but are certainly not limited to,post-surgical clips, any devices that were previously implanted (e.g.,pacing wires, electrodes, etc.), and mild to severe areas ofcalcification. The impact of calcification will be described in moredetail with reference to step 112.

With reference to an embodiment involving the mitral valve, the cineloop created for step 106 may consist of images of the mitral annulustaken on the coronal two chamber view. The cine loop allows forvisualization of the mitral annulus anatomy and pertinent landmarks suchas the mitral valve leaflet tips and the insertion points of the mitralvalve leaflets at the mitral annulus. In at least some implementations,identification should be done during the diastolic phase of the cardiaccycle, as the mitral annulus is largest in the diastolic phase. However,in an embodiment, all phases of the cardiac cycle are analyzed toaccount for the dynamic movement of the left ventricle (LV) myocardiumcontractility and the left atrium (LA) size and contractility.

For procedures relating to the aorta such as TAVR, pertinent landmarksfor step 106 may include the ostium of the left main coronary artery,the ostium of the right coronary artery, the ostium of any bypassedgrafts arising from the aorta. In an embodiment, landmark identificationand measurements described below with respect to step 108 should beperformed during the systolic phase of the cardiac cycle, as the aorticannulus is largest in the systolic phase. Implantation of thetranscatheter valve can then be performed with guidance of c-armangulation from the CT scan data set, as described in more detail below.

For procedures relating to the left atrial appendage, pertinentlandmarks for step 106 may include, for example, the pulmonary veins,the location of the Coumadin ridge, the transverse pericardial sinus,the circumflex artery or similar artery that traverses adjacent to theappendage, the mitral valve, the left atrium, the interatrial septum,and the superior vena cava and inferior vena cava transition into theinteratrial septum (to help identify the best coaxial angle to the leftatrial appendage main lobe for device positioning). C-arm angulation,described below, will be assessed to give the best projection anglesthat provide maximal delineation and separation of the left atrialappendage and the left atrium for a grasping zone (e.g., for lariatprocedures) or a landing zone (e.g., for insertion of an Amplatz device,Watchman device, or other suitable devices (e.g., suitable left atrialappendage occlusion devices).

For procedures relating to the inferior vena cava, such as heterotopictranscatheter tricuspid inferior vena cava valve implantation (TIVI),also known as caval valve implantation (CAVI), pertinent landmarks forstep 106 may include the right atrium-inferior vena cava plane, theinferior vena cava ostium, and the first hepatic vein, to cite a fewexamples. Unlike TAVR procedures, there are no valve insertion cusppoints to use as landmarks in sizing the right atrium-inferior vena cavajunction. The nadir of the right atrium-inferior vena cava plane variesfrom patient to patient based on the geometry of the patient's coronarysinus plane during inferior vena cava dilatation. C-arm angulation mayvary and should be assessed on a case-by-case basis, but in anillustrative embodiment, the C-arm projections are right anterioroblique (RAO) 33 and caudal 22.

Once the pertinent landmark(s) of the anatomical structure of interestare identified, step 108 of the method calls for measuring one or moreparameters of one or more features of the anatomical structure ofinterest, which may include, for example, and without limitation, atleast one of a circumference, a maximal diameter, or a minimal diameterof the anatomical structure of interest or a feature thereof. Themeasurements, which, in an embodiment, may be made or taken using theimage(s) of the anatomical structure of interest obtained or acquired instep 104 (e.g., 2D image(s) resulting from the sectioning of the 3Dmodel generated in step 104), are typically obtained or taken atlocations corresponding to the pertinent landmarks identified in step106, and may possibly be obtained or taken between the pertinentlandmarks as well. The measurements may also be obtained or taken indifferent planes and at different angles. It should also be noted thatat any time, it is possible to take snapshots or save different CTimages or image sets for later use, such as for reference purposes or tocreate cine loops of various phases or stages.

As a particular example, FIG. 5 shows a 3D CT model D of an anatomicalregion of interest (e.g., the thoracic region) and set of 2D CT images.The CT images comprise a first image taken along a sagittal plane(hereinafter “sagittal view A”) of the 3D model D, a second image takenalong a coronal plane (hereinafter “coronal view B”) of the 3D model D,and a third image taken along an axial plane (hereinafter “axial viewC”) of the 3D model D. The sagittal view A comprises an image of amitral valve 10 at a mitral valve leaflet insertion landmark 12. In thesagittal view A, there is a coronal plane indicator 14 and an axialplane indicator 16. The sagittal view A is acquired by aligning asagittal plane indicator 18 in a coronal view B with the sagittal planeindicator 18 in an axial view C along the mitral valve 10. The alignmentof the sagittal plane indicator 18 in the coronal and axial views B, Callows for a double oblique view to be produced of the mitral annulus inthe sagittal view A. More details regarding the alignment of indicatorsto simulate the cardiac catheterization fluoroscopic projection areprovided below. At this point, one or more measurements, for example, atleast one of a circumference 21, a maximal diameter 23, or a minimaldiameter 25 of the mitral annulus 15 may be taken in the sagittal viewA, as shown. In one embodiment, a mean diameter is derived from themaximal diameter 23 and the minimal diameter 25. FIG. 6 isrepresentative of a location at the midpoint of the mitral valve 10between the leaflet insertion landmark 12 and a mitral valve leaflet tiplandmark 20. FIG. 7 is representative of a location at the mitral valveleaflet tip landmark 20. The same or similar measurements such as thosedescribed above (e.g., with respect to FIG. 5) may be obtained at any orall of the locations depicted in FIGS. 5-7.

For the left atrial appendage, measurements for step 108 may include oneor more of: the maximal and minimal diameter of the left atrium, themeasurements of the ostium of the left atrial appendage (e.g., at leastone of a maximal diameter, a minimal diameter, an area, or acircumference); the depth of the left atrial appendage to the firstcurvature of the left atrial appendage; the circumference, diameter(maximal and/or minimal), and area at the proposed site of devicepositioning within the left atrial appendage for optimal devicedeployment; the orientation of the left atrial appendage with respect tothe left atrium (anterior or posterior facing); and the presence orabsence of a left atrial appendage clot.

For the tricuspid inferior vena cava valve, measurements for step 108may include one or more of the maximal and minimal diameter, area, andcircumference at the right atrium-inferior vena cava plane, measured, inan embodiment, approximately 1 cm below the inferior vena cava ostium,and 1 cm above the first hepatic vein. Another measurement may includethe vertical height between the inferior vena cava ostium and the firsthepatic vein. It may be desirable to mark the inferior most landmark orarea demonstrating the presence of regurgitant flow. In one embodiment,step 108 measurements for TIVI (or CAVI) procedures are taken while thepatient is lying flat on a scanner table.

In any event, and as will be described below, the measurements of theanatomical structure of interest obtained in step 108 may be used toselect a particularly sized implant, determine a point of access forpercutaneous implantation, estimate the anatomical structure volume,generate a 3D CAD model of the anatomical structure of interest,generate a 3D printed model of the anatomical structure of interest,and/or evaluate a previously implanted device, for example

Step 110 is optional and involves determining a point of access into thepatient's body for percutaneous implantation. Since the method describedherein is applicable to pre-operational planning and post-operationalanalysis, step 110 may only be necessary when the method is being usedfor pre-operational planning, and more particularly for transapicalplanning Typically, for transapical procedures, a point of access isattempted along the mid to distal anterolateral wall of the LV confirmedby a 2D transthoracic echocardiogram. Step 110 involves obtainingcertain measurements that may better approximate an ideal point ofaccess.

FIG. 8 shows a multiplane reformatted (MPR) image in the diastolic phaseof the cardiac cycle, such as the one acquired in step 102. Moreparticularly, like FIG. 5, FIG. 8 shows a 3D CT model D of an anatomicalregion of interest (e.g., the thoracic region) and set of 2D CT images.The CT images comprise a first image taken along a sagittal plane(hereinafter “sagittal view A”) of the 3D model D, a second image takenalong a coronal plane (hereinafter “coronal view B”) of the 3D model D,and a third image taken along an axial plane (hereinafter “axial viewC”) of the 3D model D. It should be noted that in at least someimplementations, all of the measurements described below with relationto step 110 should also be taken from an image while in the systolicphase of the cardiac cycle and then again in the diastolic phase toprovide a range of cardiac contractility for feasibility of catheterplacement. This allows the point of access to be represented in bothphases, and a 3D cine loop of all ten phases of the cardiac cycle can becreated with the lung fields and the point of access in view. In aparticular embodiment, to prepare for a transapical percutaneousapproach, the intersection of the coronal plane indicator 14 and thesagittal plane indicator 18 are generally aligned with the mitral valve10, the mitral annulus 15, or a mitral prosthesis in the axial view C.More particularly, without angling any of the images, a potential pointof access 30 can be identified during, for example, the diastolic phaseof the cardiac cycle as the anterolateral region of the left ventriclethat is believed to be free of the lungs, adjacent coronary vessels,ribs, and/or certain other anatomical structures on the axial plane. Theplane in which the point of access 30 is disposed may then be aligned,manually or automatically, to be parallel to the blood flow of the leftventricle. In response to the identification or assignment of the pointof access 30 and alignment of the point of access plane, the coronal andsagittal planes (and thus the corresponding plane indicators 14, 18) areautomatically generated or identified. Then, in the axial view C, theintersection of the coronal plane indicator 14 and the sagittal planeindicator 18 may be angled such that one of the indicators runs parallelto the angle of the left ventricle (LV) apex 22. If while scrollingthrough the axial and coronal views, the proposed point of access 30does not intersect any intervening anatomical structures that wereidentified/sectioned out in step 104, such as papillary muscles, ribs,vessels, or lung fields, for example, then this set of images willbecome a primary point of access image set 24. If the potential point ofaccess 30 intersects with one of the intervening anatomical structuresidentified/sectioned out in step 104, a new potential point of accesscan be chosen by the user and the above process can be repeated toobtain the primary point of access image set 24. In an embodiment, thepoint of access 30 is assigned, selected, or identified by the user. Itis contemplated, however, that in other embodiments, the identificationof the point of access may be an automated process without requiringinput from the user. Accordingly, the present disclosure is not intendedto be limited to any particular way or technique of identifying thepoint of access 30.

Other measurements may be obtained to verify the point of access 30determined or identified in step 110 and assist the physician in otherprocedural aspects. For example, FIG. 9 is an image from the primarypoint of access image set 24. In this image, the distance from thecenter of the mitral annular plane of the mitral valve 10 to theendocardium at the LV apex 22 is measured. This distance may impact thephysician's choice of sheath length as well as catheter and wire sizing,for example. As another example, the distance between ribs 26 and asurface of the skin 28 may assist in the assessment of the depth of theneedle penetration. As shown in FIG. 10, it is possible to extend themeasurement between the ribs 26 and the surface of the skin 28 out atthe same angle as the direction of the LV apex 22. This measurement maybe applied to a 3D reconstruction image/model, such as the image shownin FIG. 11, or a 3D reconstruction/model that includes a representationof the patient's skin in the model. This can provide the point of accesstrajectory from internal to the skin to the mitral annulus of the mitralvalve 10 in a 3D model, which may be viewed in still form or in a cineloop.

In an embodiment, it is possible to manipulate the 3D model generated instep 104 to remove any intervening vessels such as the left anteriordescending artery (LAD), the left internal mammary artery (LIMA), apotential bypass graft, for example, as well as any other interveninganatomical structures layer-by-layer. It may be beneficial to extend aline 32 (shown in FIG. 10) from the LAD substantially parallel to thepoint of access line to at least the surface of the skin 28. In anembodiment, line 32 is extended exactly parallel to the point of accessline; in other embodiments, however, the lines may not be exactlyparallel, but rather may be angled with respect to each other by apredetermined amount deemed suitable for the purposes described below.In any event, the distance between the line 32 and the point of access30 above the surface of the skin 28 may be measured and that measurementmay be used to estimate a distance between the trajectory path and theLAD. Knowing this distance may help to avoid unnecessary perforation ofthe LAD, for example. It may also be possible to angle the 3D model,such as the 3D model shown in FIG. 11, to show the distance moreclearly. Other measurements may include the LV wall thickness as definedbetween the endocardium and the epicardium, and the epicardial fatthickness. It may also be beneficial to measure the maximal and minimaldiameters of the left atrium (LA) while in the systolic phase and theinteratrial septum length for the particular case where the transapicalapproach fails and a transseptal approach must be attempted instead.

Another aspect that may be included in step 110 involves determining atrajectory angle at the point of access 30 and a corresponding C-armdeployment angle. With reference to FIGS. 12 and 13, a trajectory 31,and thus, the trajectory angle, may be determined by assuming aperpendicular plane 33 from, for example, an axial view/plane thatextends orthogonally from the patient's spine, and angling only in alateral direction (i.e., to the patient's left side). In an embodiment,the primary point of access image set 24 may be is used to generate theaxial view, shown in FIG. 12, and the axial view with caudal angulation,shown in FIG. 13. The C-arm deployment angle may be generally defined bythe point of access trajectory 31 and the plane 33. In the illustratedembodiment, the point of access trajectory angle is 37.0°, which may beshown on the 3D rendering as depicted in FIG. 13. The point of accesstrajectory may help with determining a C-arm deployment angle, asdescribed later with reference to FIGS. 36 and 37. It will beappreciated, however, that in other embodiments, different angles mayalso be suitable for the point of access trajectory and C-armdeployment. Additionally, intraprocedural utilization of additionalC-arm views may be provided to virtually simulate the needle position indifferent (e.g., two different) perpendicular vector views todemonstrate that the needle/catheter is coaxial to the mitral valvepoint of interest, and not angled in any direction towards pertinentanatomical structures. These pertinent structures, which may include,for example, coronary vessels, the mitral annulus, blood volume of theleft ventricle, sternotomy wires, intracardiac devices, and otherreproducible landmarks, will be generated in the C-arm overlay.

To designate the point of access on the patient, as opposed to merelyrepresenting it on a CT image, it is possible to relate the point ofaccess to readily observable anatomical structures. In one embodiment,using the primary point of access image set 24, a 2D axial view isreproduced, as shown in FIG. 14. A distance 35 of the perimeter of thebody to an area 34 at the mid-sternum can be measured. On a 3D modelobtained from the primary point of access image set 24 (e.g., model D inFIG. 8), all of the layers of skin can be restored to view the patient'souter anatomy and to view the distance in a more anatomicallyreproducible form, as shown in FIG. 15. It is then possible to manuallymark the point of access on the patient's body by measuring the distancefrom the patient's mid-sternum. This distance can also be corroboratedwith the patient's sternal notch. In an axial view from the primarypoint of access image set 24, the crosshairs can be moved back toperpendicular in order to angle the sagittal view. Then, on the sagittalview, as shown in FIG. 16, the distance from the sternal notch 36 to themid-sternum point 34, which is aligned with the point of access 30, ismeasured. FIG. 17 further illustrates this distance. As shown in FIG.18, a control measurement may be obtained by measuring the distance fromthe sternal notch 36 to the distal xiphoid process 38 along the skin'ssurface.

As a final verification for the point of access determination, it ispossible to show the point of access on a model of the body thatincludes a representation of the surface of the patient's body, and thenintervening anatomical structures may be removed by, for example, aphysician using a user interface device such as that or those describedbelow, layer-by-layer until the anatomical structure of interest is inview. The layer-by-layer removal of intervening anatomical structuresmay also be performed automatically by a system, such as the system 200described below, and played in movie form for a physician, for example.FIG. 19 shows the point of access 30 on a 3D coronal projection showingthe surface of the skin. FIG. 20 is the same representation as FIG. 19but with the outer skin layer removed. FIG. 21 is the samerepresentation that then shows the point of access 30 with the musclesremoved. FIG. 22 is the same representation that then shows the point ofaccess 30 with the ribs removed. FIG. 23 is the same representation thatshows the point of access 30 with the lungs removed. FIGS. 24-26 are thesame representations showing the point of access 30 with various cardiacstructures removed until the blood volume is shown. Finally, FIG. 27shows the point of access 30 aligned with the anatomical structure ofinterest. This layer-by-layer process can be repeated at a differentC-arm angle to show optimal C-arm viewing of the patient's anatomy whilethe procedure is occurring. It is also possible to make a cine loopshowing all of the phases of the cardiac cycle. For the cine loop, it ispreferable that the anterior sternum is removed to provide a better viewof the anatomy.

Optional step 112 of the method estimates the volume of the anatomicalstructure of interest. According to one embodiment, the volume isestimated based on the fluid capacity of the structure. For example,internal blood volume may be used to estimate the anatomical structurevolume. When a patient is injected with an iodinated contrast inpreparation for the CT procedure, the blood shows as bright areas withinthe blood vessels. Utilizing blood volume dimensions such ascircumference and area can help to predict the degree of gaps orparavalvular leakage that will appear when reconciling the anatomicalstructure size and the implant size, as described in more detail withrelation to step 114. In accordance with one embodiment, the fluidvolume is estimated using a modified Simpson's calculation. The Simpsonmethod is also known as the method of discs because it integrates volumeby fitting numerous elliptical discs into the hollow anatomicalstructure and summing up their volume. The volume of each disc isdetermined by the diameter of the disc and its height, and may becalculated according to the following equation:

Volume=(A1+A2+ . . . +An)*h;

where “h” represents the height of each disc, which is calculated as afraction of the long axis of the anatomical structure, and “A”represents the area which can be determined based on the particularlyshaped disc that will fit at that particular point. For example, if thedisc is generally circular, the area is a function of the disc'sdiameter, D:

A=π*(D/2)²;

however, it is possible to use other shapes to determine the area,depending on the best fit in a particular location. In one embodiment,the calculations are carried out more than once in different views. Forexample, it may be desirable to size the volume of a blood vessel inboth a two chamber view and a four chamber view. The cross-sectionalarea of the disc is then based on the two diameters obtained from theorthogonal views. It should also be noted that the Simpson's methoddescribed above can also be performed using an ultrasound image.

One aspect of estimating the anatomical structure volume may take intoaccount mineral deposits on the interior walls of a hollow anatomicalstructure. In one particular embodiment, the amount of calcium and itsimpact on the anatomical structure volume is determined. Heavilycalcified heart valves and vessels can create a “blooming artifact” on aCT image. The blooming artifact is a zone of haziness pictured aroundcalcium deposits identified by the CT scanner, which makes it difficultto determine the demarcation point between the vessel wall and thecalcium deposit. FIG. 28 shows a heavily calcified aortic annulus on theleft, and the right shows a “windowed down” version where the brightnessof the calcium on the screen is decreased. This shows more of a densitygradient across the calcium and minimizes the appearance of the calcium.FIG. 29 represents a beam hardening artifact which occurs within aheavily calcified aortic annulus. A beam hardening artifact may berepresented as a “gap” in the image that occurs from the x-ray beamencountering a material with a high density that disperses the x-rayradiation, creating an artificial “drop-out” effect. The arrows indicatethe beam hardening artifact which causes an obstruction in accuratelymeasuring the area because it is difficult to determine whether there isa true cut off of the annulus, or whether it is merely a beam hardeningartifact that appears as a black spotted area. The variable measurementsbetween the two images in FIG. 29 would lead to one valve size given oneset of measurements, and another valve size given another set ofmeasurements. One possible way to quantify the calcium deposit density,size, and volume is through 3D modeling estimation. To quantify thecalcium deposit and tissue differentiation needed for an adequate 3Dprinted model from CT scan data, it is possible to use currentdurometers available for 3D printers. Each durometer (e.g., ink jet fora 3D printer) is typically calibrated to a certain density. By mixingknown densities of calibrated durometers into aliquots in a premade trayfor scanning, it is possible to scan the variously calibrated durometersusing the CT scanner. Acquired images can then reflect the differenthounsfield units or density uptake of the durometers on the acquired CTimage. Data already exists on the proposed densities and hounsfieldunits for skin, tissue, blood, water, bone, and other tissuedifferentiations. By analyzing the scan from the durometer, it ispossible to know what density formula is representative of thecorresponding hounsfield unit of the particular anatomical body part(e.g., calcium). This may allow for a more accurate representation ofthe density of the anatomical structure of interest, and a more accurateassessment of the peri-operative and transcatheter needs for cathetersizing, such as the devices needed for entry into the body and deviceimplantation specifics. Validating the degree of calcium present on araw CT data acquisition in reference to known calcium models in vivo andex vivo allows for improvement in the qualification and quantificationof dimensional analysis of anatomical structure sizing.

In accordance with a particular embodiment, the blood volume, calciumdeposits, or both the blood volume and calcium deposits are used todevelop a 3D model, for example a 3D computer-aided design (CAD) model,of the anatomical structure of interest or at least a portion of theanatomical structure of interest. The 3D CAD model is constructed fromCT data that is imported into an STL file. An interfacing bridgingsoftware, such as programs developed by Mimics, can take the raw CT data(i.e., the hounsfield units) and use the changes in shade, which areindicative of changes in tissue and/or fluid composition, to developcertain shading thresholds that can be used to build a 3D model. It ispossible to sculpt the image by either paring down the CT data prior toimporting it into an STL file, or it may be possible to pare down the 3DCAD image after it has been created. FIG. 30 shows a 3D CAD model of ahollow cardiac structure developed based on internal blood volume andmodeling/showing the interior surface of the structure. FIG. 31 shows a3D CAD model of a mitral annulus showing areas of heavy calcification. A3D CAD model can also be used to print a 3D model of the anatomicalstructure of interest or a portion of the anatomical structure ofinterest, which may then be used for a variety of purposes, some ofwhich are described below.

Step 114 involves reconciling the size of the anatomical structure ofinterest and the size of an implant. The anatomical structure size maybe based on one or more of the measurements attained in step 108 of themethod, the volume estimated in step 112 of the method, or it may bebased on one or more of the measurements attained in step 108 incombination with the volume estimated in step 112. In an embodiment, theanatomical structure size is modeled using a 3D CAD model, as describedabove and depicted in FIGS. 32A and 32B which show opposite views of themitral valve 10. Included are areas of calcification 40 and 3D models oftwo potential implants, for example, 3D CAD models of two potentialimplants, or in this particular embodiment, prosthetic valves 42, 44.One or more models of implants may be imported into the 3D model of theanatomical structure and may be appropriately positioned by thephysician using, for example, one or more of the user interface devicesdescribed below, to assess issues such as the fit and suitability of oneor more potential implants. For example, this modeling allows for theanalysis of gaps 46 which are indicative of areas of potential leakage.Calcium at the mitral leaflet tips and the mitral annulus may providevarying amounts of support to the prosthetic valve. Moreover, modelingprovides a way to analyze an ideal location to anchor the implant, forexample either deeper within or higher above the calcification.

In another embodiment, the anatomical structure size is modeled using a3D printed representation of the structure itself, as shown in thevarious views depicted in FIGS. 33A-33C. FIGS. 33A-33C show a 3D printedmodel of a right atrium inferior vena cava junction 50 with a prostheticvalve 52. Given the funnel shaped anatomy of the dilated inferior venacava, it is possible to print the patient's right atrium extending intothe inferior vena cava, and in one particular case, ending just abovethe first hepatic vein. Areas of potential leakage 54 provide aphysician guidance when choosing the most appropriate valve. Accordingto another embodiment, both the 3D CAD model and the 3D printed modelallow for analysis of aortic leaflet length and leaflet motion withrespect to a potential risk of coronary ostium obstruction from valvedeployment, or leaflet obstruction of coronary ostia in prostheticvalves with higher, more prominent heights and statures. It should alsobe recognized that 3D modeling and printing work particularly well withthe left atrial appendage.

In addition to the methodology described above, another aspect of thedisclosure includes a system or apparatus for performing some or all ofthe steps of method 100 described above. With reference to FIG. 34, asystem 200 may comprise, among potentially other components, anelectronic control unit (ECU) 202, a display device 204, and one or moreuser interface devices 206.

The ECU 202 may comprise one or more electronic processing units and oneor more electronic memory devices, as well as, for example, input/output(I/O) devices and/or other known components. In another embodiment,rather than, or in addition to, the ECU 202 comprising a memory device,the system 200 may include one or more memory devices that are separateand distinct from the ECU 202 (and the processing unit(s) thereof, inparticular) but that is/are accessible thereby.

The processing unit of the ECU 202 may include any type of suitableelectronic processor (e.g., a programmable microprocessor ormicrocontroller, an application specific integrated circuit (ASIC),etc.) that is configured to execute appropriate programming instructionsfor software, firmware, programs, algorithms, scripts, etc., to performvarious functions, such as, for example and without limitation, one ormore steps of the methodologies described herein.

The memory device, whether part of the ECU 202 or separate and distincttherefrom, may include any type of suitable electronic memory means andmay store a variety of data and information. This includes, for example,software, firmware, programs, algorithms, scripts, and other electronicinstructions that, for example, are required to perform or cause to beperformed one or more of the functions described elsewhere herein (e.g.,that are used (e.g., executed) by ECU 202 to perform various functionsdescribed herein). Alternatively, rather than all of the aforementionedinformation/data being stored in a single memory device, in anembodiment, multiple suitable memory devices may be provided. These are,of course, only some of the possible arrangements, functions andcapabilities of ECU 202, as others are certainly possible. In any event,in at least some embodiments, the memory device may comprise a computerprogram product, or software, that may comprise or include anon-transitory, computer-readable storage medium. This storage mediummay have instructions stored thereon, which may be used to program acomputer system (or other electronic devices, for example, the ECU 202)to implement the control of some or all of the functionality describedherein. A computer-readable storage medium may include any mechanism forstoring information in a form (e.g., software, processing application)readable by a machine (e.g., a computer, processing unit, etc.). Thecomputer-readable storage medium may include, but is not limited to,magnetic storage medium (e.g., floppy diskette); optical storage medium(e.g., CD-ROM); magneto optical storage medium; read only memory (ROM);random access memory (RAM); erasable programmable memory (e.g., EPROMand EEPROM); flash memory; or electrical, or other types of mediumsuitable for storing program instructions. In addition, programinstructions may be communicated using optical, acoustical, or otherform of propagated signal (e.g., carrier waves, infrared signals,digital signals, or other types of signals or mediums).

The display device 204 may comprise any number of display devices knownin the art, for example and without limitation, liquid crystal display(LCD), cathode ray tube (CRT), plasma, or light emitting diode (LED)monitors or displays. The display device 204 is electrically connectedor coupled to the ECU 202, and is configured to be controlled by the ECU202 such that images or models of anatomical structures generated oracquired by the ECU 202, including those described above with respect tomethod 100, may be displayed thereon and may be used for the purposesdescribed herein. Additionally, in an embodiment wherein the ECU 202 maybe configured to generate an interactive graphical user interface (GUI)that allows, for example, a physician to manipulate images or modelsdisplayed on the display device (e.g., removing layers of a model,rotating models, etc.), facilitate the taking of measurements, etc., thedisplay device 204 may also display such a GUI. In any event, thedisplay device 204 is configured to receive electrical signals from theECU 202 and to display content represented by the received signals whichmay be viewed by, for example, a physician.

The user interface device(s) 206 may comprise any number of suitabledevices known in the art. For example, and without limitation, the userinput device(s) 206 may comprise one or a combination of a touch screen(e.g., LCD touch screen), a keypad, a keyboard, a computer mouse orroller ball, and/or a joystick, to cite a few possibilities. In certainimplementations, the display device 204 and user input device 206 may becombined together into a single device. Regardless of the particularform the user interface device(s) take, the user input device(s) 206 maybe electrically connected or coupled (e.g., via wired or wirelessconnections) to the ECU 202, and are configured to facilitate a measureof communication between a user (e.g., physician) and the system 200,and the ECU 202 thereof, in particular. More particularly, the userinterface device(s) 206 may allow a physician to manipulate images ormodels displayed on the display device 204 (e.g., rotate images ormodels, strip away or add layers to a model or image, move modelsrelative to each other, etc.), to take desired measurements ofanatomical structures represented by or in the images or modelsdisplayed on the display device 204, etc.

While certain components of the system 200 have been described above, itwill be appreciated that in some implementations, the system 200 mayinclude more or fewer components than are included in the arrangementdescribed above. Accordingly, the present disclosure is not intended tobe limited to any particular implementation(s) or arrangement(s) of thesystem 200.

FIGS. 35 and 36 can be used to simulate the cardiac catheterizationfluoroscopic projection, which may be done for purposes of steps 108 andsteps 110 above. A maximum intensity projection (MIP), which displaysthe brightest voxel of a CT image, can be helpful to visualizevasculature. With reference to the mitral annulus example, MIP inversionmay be applied, and a 3D image may be built that includes in the fieldof view: the ribs, spine, left atrium, left ventricle, aorta, the aorticvalve, and the first hepatic vein, for example. This 3D image can thenbe projected in a black-white radiograph simulation. The originalperspective of the mitral annular sizing plane can be restored into the3D MIP inverted image and the spinous processes should be marked in thecoronal view and the sagittal view, which allows for a physicaldemarcation for the trajectory of the C-arm transapical angulation. Todetermine C-arm angles, as shown in FIG. 35, the mitral valve planeimage may be restored. All plane indicators should be applied to the 3Dimage D. Then, in the 3D image D, which is shown enlarged in FIG. 36, itis possible to rotate the 3D image in the direction indicated by thearrow to ultimately align the axial plane indicator 16 and the sagittalplane indicator 18 such that they intersect perpendicularly, as shown inFIG. 37. FIG. 37 shows the projection of the C-arm angulation across themitral valve horizontal plane for proposed transapical access. Amulti-image (e.g., 20-image) snapshot view may be created that shows themovement of the 3D inverted MIP image 90 degrees superiorly, theninferiorly, then to the right anterior oblique (RAO) position. Thisreduces the amount of iodinated contrast that needs to be administeredand reduces the amount of radiation applied to the patient, while givingphysicians more insight on what to anticipate during the procedure. Thistechnique can be applied to other anatomical structures for adequatelocalization in any fluoroscopic suite utilizing C-arm angulation andprojection of images onto a visual display.

With reference to the tricuspid inferior vena cava valve (or CAVI)example provided above, a similar volume rendered MIP may be developed.The MIP inversion and 3D volume image can include segmentation of theribs, spine, right atrium, right ventricle, inferior vena cava, and thefirst hepatic vein which may be projected in a black and whiteradiograph simulation. Original snapshots may be restored one at a timeof the right atrium-inferior vena cava plane, and the inferiorcava-hepatic vane plane separately into the 3D inverted volume MIP. Itmay be desirable to mark the corresponding spinous processes in thecoronal and sagittal views in each respective plane. C-arm angles may beobtained by aligning the axial and sagittal planes in the 3D window suchthat they interest perpendicularly. A multi-image (e.g., 20-image)snapshot video may be made to show the movement of 3D inverted MIP 90degrees superiorly, then inferiorly, then to the RAO position from thisbaseline angulation. During an inferior vena cava procedure, 2D and 3Dtranesophageal echocardiography (TEE) may be used to survey the rightatrium for any clots or pericardial effusion, intraprocedure stent ordevice migration, observance of pre- and post-procedure coronary sinusflow, and the presence or absence of a paravalvular leak. A newpericardial effusion could suggest concern for iatrogenic perforation ofthe right atrium, and if such an effusion is present, cine loops can bemade of the right atrium-inferior vena cava junction in an oblique andaxial cross-sectional view which could indicate a leak in the absence ofcontrast extravasation to adjacent structures. Non-traditional views mayprovide preferable angles for TEE in TIVI cases. To visualize the rightatrium-inferior vena cava junction, it is possible to start in a 4chamber view and advance to the level of the coronary sinus. Then, theprobe angulation may be increased to bring the mouth of the inferiorvena cava into the plane. Other parameters that may be evaluated includethe right ventricle size, the right ventricle fractional area change(FAC), gradients across the implanted device, pulmonary artery systolicpressure, and the tricuspid annular plane systolic excursion (TAPSE).Pulsed wave Doppler may be run across the right atrium-inferior venacava junction to follow peak and/or mean gradients across the implantedvalve. The hepatic vein and pulmonary vein Doppler flow patterns mayalso be evaluated. After the procedure, gated computer tomographyangiography (CTA) or clinical target volume (CTV) of the abdomen may beperformed to evaluate function and positioning of the implanted valve. Atwo-phase gated CTA and CTV may be initially performed, although a CTVmay not be necessary, as the gated CTA abdomen images in and ofthemselves could be adequate for evaluation of regurgitant flow andvalve function. Cine loops through the axial and sagittal slices of theinferior vena cava demonstrates opening and closure of the implantedvalve device by the dynamic change in hounsfield units across the valveand a demonstrable lack of flow into the distal inferior vena cava withvalve leaflet closure, and flow with leaflet opening.

It is to be understood that the foregoing is a description of one ormore embodiments of the invention. The invention is not limited to theparticular embodiment(s) disclosed herein, but rather is defined solelyby the claims below. Furthermore, the statements contained in theforegoing description relate to particular embodiments and are not to beconstrued as limitations on the scope of the invention or on thedefinition of terms used in the claims, except where a term or phrase isexpressly defined above. Various other embodiments and various changesand modifications to the disclosed embodiment(s) will become apparent tothose skilled in the art. For example, the specific combination andorder of steps presented is just one possibility, as the present methodmay include a combination of steps that has fewer, greater, or differentsteps than that shown here. All such other embodiments, changes, andmodifications are intended to come within the scope of the appendedclaims.

As used in this specification and claims, the terms “e.g.,” “forexample,” “for instance,” “such as,” and “like,” and the verbs“comprising,” “having,” “including,” and their other verb forms, whenused in conjunction with a listing of one or more components or otheritems, are each to be construed as open-ended, meaning that the listingis not to be considered as excluding other, additional components oritems. Other terms are to be construed using their broadest reasonablemeaning unless they are used in a context that requires a differentinterpretation.

1. A method of analyzing a hollow anatomical structure of interest forpercutaneous implantation, comprising the steps of: acquiring image datarelating to an anatomical region of interest that at least partiallyincludes the anatomical structure of interest; generating a segmentedmodel of the anatomical region of interest using the acquired imagedata; obtaining one or more images of the anatomical structure ofinterest by sectioning out intervening anatomical structures from thesegmented model; identifying one or more pertinent landmarks of theanatomical structure of interest in the one or more acquired images;measuring at least one of a circumference, a maximal diameter, or aminimal diameter of one or more features of the anatomical structure ofinterest contained in the one or more acquired images to determine ananatomical structure size; and reconciling the anatomical structure sizeand an implant size.
 2. The method of claim 1, wherein he acquired imagedata comprises computed tomography (CT) data and the segmented modelcomprises a segmented CT model.
 3. The method of claim 1, furtherincluding the step of determining a point of access for percutaneousimplantation.
 4. The method of claim 3, further comprising verifyingthat the point of access does not intersect any anatomical structures byremoving one or more layers of the segmented model.
 5. The method ofclaim 3, further comprising determining a trajectory angle at the pointof access.
 6. The method of claim 1, further including the step ofestimating an anatomical structure volume.
 7. The method of claim 1,wherein the anatomical structure of interest is a mitral valve.
 8. Themethod of claim 7, wherein the one or more pertinent landmarks compriseone or more of: a mitral valve leaflet tip and an intersection point ofthe mitral valve leaflets and the annulus of the mitral valve.
 9. Themethod of claim 1, wherein the anatomical structure of interest is aleft atrial appendage.
 10. The method of claim 9, wherein the one ormore landmarks comprise one or more of: a pulmonary vein; a location ofthe Coumadin ridge; the transverse pericardial sinus; the circumflexartery; the mitral valve; the left atrium, the interatrial septum, andthe superior vena cava and inferior vena cava transition into theinteratrial septum.
 11. The method of claim 1, wherein the anatomicalstructure of interest is a tricuspid inferior vena cava valve.
 12. Themethod of claim 11, wherein the one or more landmarks comprise one ormore of: the right atrium-inferior vena cava plane, the inferior venacava ostium, and the first hepatic vein.
 13. The method of claim 1,further including creating a computer aided design (CAD) model of atleast a portion of the anatomical structure of interest, and thereconciling step comprises importing a model of the implant into the CADmodel.
 14. The method of claim 1, further including acquiring a printedmodel of at least a portion of the anatomical structure of interest, andthe reconciling step comprises inserting a physical model of the implantinto the printed model.
 15. A method of analyzing a hollow anatomicalstructure of interest for percutaneous implantation, comprising thesteps of: acquiring a model of an anatomical region of interest that atleast partially includes the anatomical structure of interest, whereinthe model is generated from image data relating to the anatomical regionof interest; obtaining one or more images of the anatomical structure ofinterest by sectioning out intervening anatomical structures from themodel; acquiring data relating to the anatomical structure of interestfrom the one or more images of the anatomical structure of interest; anddetermining a size of an implant to be implanted into the anatomicalstructure of interest based on the acquired data.
 16. The method ofclaim 15, wherein the step of acquiring data relating to the anatomicalstructure of interest comprises acquiring one or more measurementsrelating to one or more features of the anatomical structure ofinterest, and the determining step comprises determining the size of theimplant based on the acquired measurement(s).
 17. The method of claim15, wherein the step of acquiring data relating to the anatomicalstructure of interest comprises acquiring data relating to a bloodvolume of the anatomical structure of interest.
 18. The method of claim17, further comprising generating a model of the anatomical structure ofinterest based on the blood volume data, and wherein the determiningstep comprises determining the size of the implant using the modelgenerated from the blood volume data.
 19. The method of claim 15,wherein the model generated from the blood volume data comprises a modelof the interior surface of the anatomical structure of interest.
 20. Anon-transitory, computer-readable storage medium storing instructionsthereon that when executed by one or more electronic processors causesthe one or more processors to carry out the method of: acquiring a modelof an anatomical region of interest that includes the anatomicalstructure of interest, wherein the model is generated from image datarelating to the anatomical region of interest; obtaining one or moreimages of the anatomical structure of interest by sectioning outintervening anatomical structures from the model; acquiring datarelating to the anatomical structure of interest; and determining a sizeof an implant to be implanted into the anatomical structure of interestbased on the acquired data.